Edible fungus has long been used as a nutritional aid or health food in Asia, with Ling-Zhi, the Chinese name for one form of mushroom Ganoderma lucidum, being the most popular and oldest mushroom known to have medicinal usages for thousands years. Various active compounds have been isolated from Ganoderma including triterpenoids, polysaccharides, proteins, nucleic acids, polypeptides and phyto-sterols and etc. Among them, triterpenoids are the most important components in Ling-Zhi with significant pharmacological activities such as inhibition of cholesterol synthesis, antitumor, antihypertensive and etc. Triterpenoids are generally known to include various types of ganoderic acids (GAs), ganodermic acids (GMAS), ganoderic alcohols, ganoderic ketones and ganoderic aldehydes and etc. Prior studies have demonstrated that GAs possess cytotoxic and/or anti-proliferative effects against tumor cells. For example, ganoderic acid D (GAD) was found to inhibit the proliferation of HeLa human cervical carcinoma (Yue et al., Mol Cell Proteomics (2008) 7, 949-961); ganoderic acids A and H (GAA and GAH) were demonstrated to suppress growth and invasive behavior of breast cancer cells (Jiang et al., Int J Mol Med (2008) 21, 577-584); ganoderic acid X (GAX) was found to inhibit topoisomerases and induced apoptosis in liver cancer cells (Li et al., Life Sci. (2005) 77, 252-265); and ganoderic acid Me (GAMe) effectively inhibited tumor growth, and lung metastasis (Wang et al., Int Immunopharmacol (2007) 7, 864-870). As to ganodermic acid S (GMAS), it was found to induce aggregation of platelets (Wang et al., Biochim. Biophys. Acta. (1989) 986, 151-160), inhibit function of platelets (Wang et al., Biochem. J. (1991) 277 (Pt 1), 189-197), as well as the signaling cellular responses induced by thromboxane A2 (Su et al., Biochem. Pharmacol. (1999) 58, 587-595; Su et al., Biochim. Biophys. Acta. (1999b) 1437, 223-234) or prostaglandin E1 (Su et al., Thromb. Res. (1999c) 99, 135-145) in platelets.
In the past, Ling-Zhi only grows naturally and rarely on aged trees in steep mountains, however, with the improvement on cultivating techniques, it is now possible to cultivating Ganoderma lucidum in artificial environment. JP-A-57014816 disclosed a method of cultivating Ganoderma lucidum karst, by planting a seed fungus (spore) into a material wood, however, such method is disadvantages from the viewpoint of productivity, for it takes much labor in inoculation and, the culturing time is long, 120 to 150 days for cultivating, maturing and growing of fungi; and the resulting fungi are different from the naturally grown fungi in terms of the content and/or profiles of the active components (i.e., triterpenoids).
In view of the forgoing, there exists a need in the related art an improved method of cultivating Ganoderma lucidum so that large amount of triterpenoids may be produced in a relatively short period of time for medicinal application.